Broadcast Address
Last address in an IPv4 subnet, used to send traffic to every host at once.
The broadcast address is the last address in an IPv4 subnet and is used to send traffic to every host in that subnet simultaneously. Because it represents "all hosts" on the local segment, it cannot be assigned to an individual device and is reserved by the protocol itself.
When a host transmits a packet to the broadcast address, a single frame is placed on the local network and every host in the same subnet receives and processes it. This differs from unicast, where a packet is delivered to one specific host, and from multicast, where a packet is delivered to a defined group of subscribers rather than the entire subnet.
For a subnet such as 192.168.1.0/24, the broadcast address is 192.168.1.255. The first address (192.168.1.0) is the network address and the last address (192.168.1.255) is the broadcast address, which is why neither can be assigned as a normal host address and why a /24 yields 254 usable addresses rather than 256.
The broadcast address is determined directly by the subnet mask and prefix length of the subnet, and is a core concept in CIDR-based subnet planning. IPv6 does not use broadcast at all and relies on multicast instead.
Points clés
- Last address in an IPv4 subnet
- Sends traffic to all hosts in the subnet
- Not assignable to individual devices
- Determined by subnet mask and prefix length
- Commonly used in local network communication
- Different from unicast and multicast
- Important in subnet calculations
- Used in IPv4 networks